1. A process for treating a crude product of 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate by a non-aqueous method is characterized by comprising the following steps: the method comprises the following steps: adding a filter aid into the crude product of the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, sequentially carrying out primary coarse filtration and secondary fine filtration under the action of the filter aid to obtain filtrate, and refining the filtrate to obtain the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate product.

2. The process of claim 1 for the non-aqueous treatment of crude 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, wherein: the crude product of the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate is a material obtained by catalyzing condensation of isobutyraldehyde by using alkali or alkaline earth metal carbonate as a catalyst; the catalyst is sodium carbonate and sodium hydroxide.

3. A process according to claim 1 or 2 for the non-aqueous treatment of crude 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, wherein: in the crude 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, the catalyst exists in the form of particles, and the particle size distribution of the catalyst is as follows: 0.5-1% of particle size 1-40 μm, 80-85% of particle size 40-100 μm, and 19.5-14% of particle size 100-250 μm.

4. The process of claim 1 for the non-aqueous treatment of crude 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, wherein: the filter aid is a material with compressibility index less than 0.15; the particle size of the filter aid is 50-100 mu m.

5. A process according to claim 1 or 4 for the non-aqueous treatment of crude 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, wherein: the filter aid is selected from diatomite and precipitated calcium carbonate.

6. The process of claim 5, wherein the process comprises the steps of: the filter aid is selected from diatomite.

7. The process of claim 1 for the non-aqueous treatment of crude 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, wherein: the using amount of the filter aid is 0.05-0.1% of the mass of the crude product of the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate.

8. The process of claim 1 for the non-aqueous treatment of crude 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, wherein: the filter of the primary coarse filtration is selected from filter paper or an industrial grade filter pipe; the filter of the secondary precise filtration is selected from filter paper or an industrial grade filter pipe; the aperture of the filter for the primary coarse filtration is 25-50 μm; the aperture of the filter for the secondary precise filtration is 0.4-3 μm.

9. The process of claim 1 for the non-aqueous treatment of crude 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, wherein: the filtration flux of the crude 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate in a filter for primary coarse filtration and a filter for secondary fine filtration is 100-3000 kg/(m)²H), the filtering pressure difference is 0.098-0.5 MPa, and the filtering temperature is normal temperature.

10. The process of claim 1 for the non-aqueous treatment of crude 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, wherein: refining the filtrate under the conditions that the vacuum degree is 0.095-0.099 MPa and the temperature is 120-180 ℃, and collecting fractions with the tower top temperature of 115-117 ℃ to obtain a 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate product.

Background

2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate is a film-forming additive widely applied to coatings, and the industrial production technology is as follows: isobutyraldehyde is used as a raw material and is condensed under the action of an inorganic alkali/alkaline earth metal carbonate catalyst to obtain 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate. Because the catalyst is inorganic salt and is insoluble in oily products, the obtained crude product of the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate is milky opaque suspension in appearance, the pH value of the suspension is alkaline, isobutyric acid is a byproduct in a condensation reaction of isobutyraldehyde, the isobutyric acid reacts with the alkaline catalyst to form isobutyrate, and the organic salt is also alkaline. At present, the characteristic that a basic catalyst and a basic organic acid salt have high solubility in water and oily substances such as 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate and the like have low solubility in water is utilized, and a method of washing with a large amount of water is adopted to remove the basic catalyst and the basic organic acid salt from the oily substances such as 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate and the like to obtain the oily substances containing 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate which are close to neutral, so that when products are rectified, the yield reduction of the products caused by the decomposition of the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate by the basic catalyst during high-temperature cooking is avoided.

A large amount of high-concentration wastewater is generated in the washing process, and the wastewater can be reduced to be discharged in a pipe within an acceptable range of a park sewage plant through triple-effect evaporation, Fenton oxidation, biochemical process, anaerobic process, hydrolysis and aerobic process. The process can not realize the cyclic utilization of the wastewater, the economic loss caused by wastewater treatment is huge every year, and the problem becomes the bottleneck problem of the sustainable development of enterprises and is urgently solved.

In order to solve the problem of a large amount of waste water generated by enterprises, the enterprises adopt a method of recycling all washing water, and the waste water is expected to be recycled, but because water-soluble organic acid salts such as isobutyrate exist in a crude product of 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, the organic acid salts are continuously accumulated in the washing water when the washing water is recycled, so that the content of the organic acid salts in a water phase is higher and higher, and the COD value in the waste water is as high as 40 ten thousand mg/L when the washing water is finally recycled, so that the waste water is converted into high-concentration organic hazardous waste, the treatment cost is increased sharply, and the bottleneck problem of sustainable development of the enterprises is formed.

Disclosure of Invention

The catalyst for producing 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate by condensation of isobutyraldehyde is usually an inorganic strongly basic substance such as sodium carbonate, sodium hydroxide, etc., and the inorganic strongly basic substance such as sodium carbonate is hardly dissolved in 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate. Aiming at the problems of large waste water generation amount and unused resources in waste water in the process of removing basic catalyst in 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate by washing, the invention separates inorganic strong alkaline substances such as sodium carbonate and the like from the crude product (oily substance) of 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate by adding a filter aid with small compression index into the crude product of 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate through two-stage filtration under non-aqueous condition, the other basic substance, namely organic acid salt is dissolved in the oily substance, the basic organic acid salt can not be hydrolyzed to form hydroxide under non-aqueous condition without catalytic function, even if the basic substance can not be separated from the oily substance through a filtration mode, the process of obtaining 2 from the oily substance through a refining section can not be influenced, 2, 4-trimethyl-1, 3-pentanediol monoisobutyrate product.

The filter cake formed by inorganic strong alkaline substances such as sodium carbonate and the like in the filtering process belongs to a compressible filter cake, and the filter cake is gradually compressed to form a compact filter cake along with the increase of the filtering pressure in the filtering process, so that the void ratio in the filter cake is gradually reduced, the filtering flux is reduced, and the filtering efficiency is influenced. Judging the filtering efficiency to be the size of a filtering constant, wherein the filtering constant is calculated by the following formula:

in the formula: k is a filtration constant; delta P_mFiltering the pressure difference; mu is the viscosity of the filtrate;is the solid content; r is₀Specific resistance coefficient, which depends only on the system; s is the compressibility index of the filter cake.

From the above formula, it can be seen that, for the selected filtration system, μ,r₀Are all constant values, filter constant and (Δ P)_m)^1-sThe filter cake compression index is reduced and the filtration pressure is increased in the filtration process, so that the filter cake compression index is in direct proportion relationship, and the filtration is facilitated. Aiming at the filtering characteristic, a filter aid with a small compression index is added into the crude product of 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, so that the filtering constant is increased and the filtering efficiency is improved.

The purpose of the invention is realized by the following technical scheme:

a process for treating crude 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate by a non-aqueous method, comprising: adding a filter aid into the crude product of the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, uniformly mixing, sequentially carrying out primary coarse filtration and secondary fine filtration under the action of the filter aid to obtain filtrate, and refining the filtrate to obtain the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate product.

The crude product of the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate is a material obtained by catalyzing condensation of isobutyraldehyde by using alkali or alkaline earth metal carbonate as a catalyst; the catalyst is preferably inorganic strong alkaline substances such as sodium carbonate and sodium hydroxide. The dosage of the catalyst is 1-5% of the mass of isobutyraldehyde.

The catalyst exists in the form of small particles in a crude product of 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, and the particle size distribution of the catalyst is as follows: the particle size is 1-40 μm (i.e. the particle size is not less than 1 μm and not more than 40 μm) 0.5-1%, the particle size is 40-100 μm (i.e. the particle size is not less than 40 μm and not more than 100 μm) 80-85%, and the particle size is 100-250 μm (i.e. the particle size is not less than 100 μm and not more than 250 μm) 19.5-14%.

The filter aid is a material with compressibility index s less than 0.15, and is selected from diatomite (s-0.098) and precipitated calcium carbonate (s-0.14), preferably diatomite.

The particle size of the filter aid particles is 50-100 mu m.

The using amount of the filter aid is 0.05-0.1% of the mass of the crude product of the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate.

The primary coarse filtration filter operates in series with the secondary fine filtration filter.

The filter of the primary coarse filtration is selected from conventional filter paper or an industrial grade filter pipe; the filter of the secondary precise filtration is selected from conventional filter paper or an industrial grade filter pipe; the industrial grade filter tube is a 304 stainless steel powder metal sintered filter tube.

The aperture of the filter for the primary coarse filtration is 25-50 μm; the aperture of the filter for the secondary precise filtration is 0.4-3 μm.

The filtration flux of the crude 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate in a filter for primary coarse filtration and a filter for secondary fine filtration is 100-3000 kg/(m)²H), the filtering pressure difference is 0.098-0.5 MPa, and the filtering temperature is normal temperature. When the filtration pressure difference is increased to > 0.5MPa,the filter cake is stripped from the filter by conventional techniques such as back-purging, thereby restoring the filtering capacity of the filter.

Refining the filtrate under the conditions that the vacuum degree is 0.095-0.099 MPa and the temperature is 120-180 ℃, and collecting the fraction at the tower top temperature of 115-117 ℃ to obtain a 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate product with the content of more than or equal to 98.5%.

Compared with the prior art, the invention has the beneficial effects that:

(1) compared with the traditional process, the invention eliminates a water-using working section, avoids the generation of waste water, greatly reduces the production cost and the waste water treatment cost, and has great environmental benefit and economic benefit.

(2) The catalyst removal rate of the invention reaches 100%, and by adding a small amount of low compressibility index filter aid, the filtration efficiency can be improved, the process flow is simplified, and the operation cost is greatly reduced.

Detailed Description

The technical solution of the present invention will be described in further detail with reference to examples.

Example 1

The crude 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate prepared by catalyzing isobutyraldehyde with sodium carbonate has the following particle size distribution of solid particles (namely, sodium carbonate): 0.6% of particles having a particle diameter of 1 to 40 μm, 84.6% of particles having a particle diameter of 40 to 100 μm, and 14.8% of particles having a particle diameter of 100 to 250 μm.

At normal temperature, 500g of 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate crude product is taken, 0.25g of diatomite with the particle size of 60-80 mu m is added, the mixture is uniformly stirred, and the filtering area is 0.005m²Performing primary coarse filtration in the filter (filter medium: filter paper with the aperture of 30-50 μm), wherein the filtration time is 1h, and finishing the coarse filtration; then passing through a filter with the same filtering area of 0.005m²The filter (filter medium: filter paper with the aperture of 1-3 mu m) is subjected to secondary precision filtration, and the filtration time is 0.25 h; the filtration pressure difference of the primary coarse filtration and the secondary fine filtration is 0.098MPa, and the total amount of the obtained filter cake accounts for 0.92 percent of the total mass of the crude product.

And (3) rectifying the filtrate obtained by filtering under the conditions that the vacuum degree is 0.097MPa and the temperature is 150 ℃, and collecting the fraction at the temperature of 115-117 ℃ at the top of the tower to obtain the product of which the purity of the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate is 98.7%.

Example 2

The crude 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate prepared by catalyzing isobutyraldehyde with sodium carbonate has the following particle size distribution of solid particles (namely, sodium carbonate): 0.6% of particles having a particle diameter of 1 to 40 μm, 84.6% of particles having a particle diameter of 40 to 100 μm, and 14.8% of particles having a particle diameter of 100 to 250 μm.

At normal temperature, 500g of 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate crude product is taken, 0.5g of precipitated calcium carbonate with the particle size of 50-100 mu m is added, the mixture is stirred uniformly, and the filtering area is 0.005m²The filter (filter medium: filter paper with the aperture of 30-50 mu m) is subjected to primary coarse filtration for 1.3h, and then the filter medium is subjected to filtration with the same filtration area of 0.005m²The filter (filter medium: filter paper with the aperture of 1-3 mu m) is subjected to secondary precision filtration, and the filtration time is 0.25 h: the filtration pressure difference of the primary coarse filtration and the secondary fine filtration is 0.098MPa, and the total amount of the obtained filter cake accounts for 0.97 percent of the total mass of the crude product.

And (3) rectifying the filtrate obtained by filtering under the conditions that the vacuum degree is 0.097MPa and the temperature is 150 ℃, and collecting the fraction at the temperature of 115-117 ℃ at the top of the tower to obtain the product of which the purity of the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate is 98.7%.

Example 3

2 filter areas are all 1m²The filters are connected in series, and the filter pipes of the two filters are both 304 stainless steel powder metal sintered filter pipes; the first filter has a filter pore size of 25-40 μm (for primary coarse filtration), and the second filter has a filter pore size of 1-3 μm (for secondary fine filtration).

2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate crude product (in the same way as in example 1, diatomite with the particle size of 60-80 μm is added as a filter aid, the adding amount of the diatomite is 0.1% of the mass of the crude product) passes through two filters in sequence at the speed of 2000kg/h, the pressure difference of a first filter is 0.15MPa, the pressure difference of a second filter is 0.18MPa, after filtration for 1 hour, the filtration pressure difference of the first filter is increased to 0.52MPa, the pressure difference of the second filter is increased to 0.20MPa, at the moment, filtration is stopped, and the first filter is subjected to back flush to remove filter cakes. After the first filter is backflushed to remove filter cakes, the materials are fed at the speed of 2000kg/h again, the pressure difference of the first filter is changed to 0.22MPa, and the pressure of the second filter is still 0.20 MPa. The mixture is filtered and backflushed in this way, and colorless and transparent filtrate is obtained.

Rectifying the filtrate under the conditions of vacuum degree of 0.095MPa and 160 ℃, and collecting the fraction at the temperature of 115-117 ℃ at the top of the tower to obtain the product with the purity of 98.6 percent of 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate.

Example 4

2 filter areas are 2m²The filters are connected in series, and the filter pipes of the two filters are both 304 stainless steel powder metal sintered filter pipes; the first filter has a filter pore size of 25-40 μm (for primary coarse filtration), and the second filter has a filter pore size of 1-3 μm (for secondary fine filtration).

2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate crude product (in the same example 1, diatomite with the particle size of 60-80 μm is added as a filter aid, the adding amount of the diatomite is 0.1% of the mass of the crude product) sequentially passes through two filters at the speed of 2000kg/h, the pressure difference of a first filter is 0.12MPa, the pressure difference of a second filter is 0.15MPa, and after filtration for 1 hour, the filtration pressure difference of the first filter is increased to 0.37MPa, and the pressure difference of the second filter is increased to 0.18 MPa; and (5) continuing filtering for 0.5 hour, increasing the filtering pressure difference of the first filter to 0.51MPa, and increasing the pressure difference of the second filter to 0.24MPa, at the moment, stopping filtering, and performing back flushing on the first filter to remove filter cakes. After the first filter is backflushed to remove filter cakes, the materials are fed at the speed of 2000kg/h again, the pressure difference of the first filter is changed to 0.14MPa, and the pressure of the second filter is still 0.24 MPa. The mixture is filtered and backflushed in this way, and colorless and transparent filtrate is obtained.

Rectifying the filtrate under the conditions of vacuum degree of 0.097MPa and 155 ℃, and collecting the fraction at the temperature of 115-117 ℃ at the top of the tower to obtain the product with the purity of 98.8 percent of 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate.

Comparative example 1

The crude 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate prepared by catalyzing isobutyraldehyde with sodium carbonate has the following particle size distribution of solid particles (namely, sodium carbonate): 0.6% of particles having a particle diameter of 1 to 40 μm, 84.6% of particles having a particle diameter of 40 to 100 μm, and 14.8% of particles having a particle diameter of 100 to 250 μm.

At normal temperature, 500g of 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate crude product is taken, and the filtration area is 0.005m²The filter (filter medium: filter paper with the aperture of 30-50 mu m) is subjected to primary coarse filtration for 2 hours, and then the coarse filtration is finished, and the filtration area is also 0.005m²The filter (filter medium: filter paper with the aperture of 1-3 mu m) is subjected to secondary precision filtration, and the filtration time is 0.25 h; the filtration pressure difference of the primary coarse filtration and the secondary fine filtration is 0.098MPa, and the total amount of the obtained filter cake accounts for 0.87 percent of the total mass of the crude product.

And rectifying the filtrate obtained after filtration under the conditions that the vacuum degree is 0.097MPa and the temperature is 150 ℃, and collecting the fraction at the temperature of 115-117 ℃ at the top of the tower to obtain the product of which the purity of the 2,2, 4-trimethyl-1, 3-pentanediol monoisobutyrate is 98.6%.

From the filtration results, the filtration time was doubled, i.e., the filtration efficiency was decreased by one time, compared to example 1, due to the absence of the addition of the filter aid, indicating that the addition of the filter aid can significantly improve the filtration efficiency.